Dual wall turbine blade and vane airfoils may be manufactured by bonding a skin to a spar. Typically, both the skin and spar are formed by casting, although different manufacturing techniques may be employed. For example, the spar may be machined from a bar stock, and the skin may be in the form of sheet meta, however other material configurations are contemplated herein. In any event, a number of material combinations may be proposed for use as the skin and spar materials for bonded dual wall airfoils, for example, turbine blade airfoils, and turbine vane airfoils. These materials may have a wide range of material characteristics and properties, which would affect the failure modes of the dual wall bonded airfoil and the materials' response to complex loading in service in a gas turbine engine. The complex configurations of dual wall bonded airfoils and the complex operating conditions in which such airfoils operate in the gas turbine make it difficult to determine the relative merits of the various material combinations analytically. It would be desirable to be able to test various combinations of materials for the spar and skin, as well as the bond joints where the skin is attached to the spar, in order to perform life characterization of such combinations under the mechanical and thermal-mechanical loading conditions anticipated in service in the engine. However, the loading on such airfoils is difficult and expensive to capture in test rigs, since such testing typically requires fabricating dual wall bonded airfoils from each of the material combinations, and then testing the airfoils in expensive custom-built test rigs that secure the airfoils to the rig, e.g., via a rotating turbine disk, and subject the airfoils to the mechanical and thermal loading conditions seen in the engine.
Accordingly, what is needed in the art is an effective way to test skin and spar material combinations and the bond joints therebetween in a manner that captures thermal, mechanical and/or thermal-mechanical loading.